Hyperpronation and flat feet (“fallen arches”) are relatively common conditions of the feet that cause pain, such as during sports or daily activities like walking. These conditions can be caused by collapse thru the sinus tarsi. The sinus tarsi is a space between the talus and the calcaneus. It is funnel shaped with the larger opening on the lateral side of the foot progressing across the foot to end in a small medial opening between the two aforementioned bones. This lateral opening or space between the bones is normally maintained by the tension of ligaments located on the medial side of the talus and the posterior side of the calcaneus. When these ligaments fail due to either injury or disease, the talus is allowed to sublux or deviate from its normal position atop the calcaneus. This subluxation shifts the location of the calcaneus laterally (causing flatfoot), and allows the arch of the foot to collapse, increasing pronation. When this happens, the funnel shaped lateral opening of the sinus tarsi disappears.
Common noninvasive treatments for hyperpronation and flat feet include the use of foot orthotics and shoe modifications. Situations in which these treatments fail to relieve symptoms may require implantation of a subtalar arthroereisis, a type of “bone block”, in the sinus tarsi to “reopen” the collapsed sinus tarsi. The subtalar arthroereisis typically acts as a spacer to limit motion of the talus. However, after implantation of current subtalar arthroereisis systems, the arthroereisis often become loose within the sinus tarsi, causing painful irritation of the surrounding tissue. Furthermore, these systems are not stable enough to accurately reconstitute the anatomy of the sinus tarsi. Once the system fails, removal is mandatory, with resultant painful collapse and the need for a formal subtalar arthrodesis (joint fusion).
Thus, there is a need in the implant field to create an improved subtalar arthroereisis. This invention provides such an improved subtalar arthroreisis.